Starches in the Mash: Mr. Wizard
Q
Do starches quickly become solubilized or do they remain trapped in the grist when the strike water is added? This question is regarding how a recirculating system behaves and whether there would be any effect if the recirculating wort were being heated above a desired mash temperature when passed through a heat exchanger. Are the starches and their breakdown products mostly in solution along with the enzymes, or are they still in the grist solids for most of the mash time?
Vadim Kotlyar
Hartford, Connecticut
A
This is really a great question and one that brewers started contemplating shortly after RIMS (recirculating infusion mashing systems) brewing became popular. The two main goals of malt milling are particle size reduction and preservation of malt husk material. And when grist and strike water are combined soluble solids in the malt migrate from the grist particles into wort.
But not all of the starch molecules leave the grist particle immediately. This means that enzymatic degradation occurs both in the bulk liquid phase of the mash and within the grist particles that still contain starch and enzymes. In order for malt enzymes to act upon their starchy substrates, these two players must come into physical contact and the starch molecules that move into the bulk aqueous phase are much more available to enzymatic encounter than the starches that remain trapped within grist particles. If the only thing we wanted to do in the
brewhouse was convert malt starches into fermentable sugars, we would mill very finely to speed up starch conversion. Since we need the malt husk for wort separation it is important to strike a balance between these two conflicting objectives.
The important thing with this discussion is that malt enzymes are also partitioned in the mash; some are floating about in the bulk aqueous phase and some are within malt particles. Some of the enzymes that are floating about in the open ocean of wort are exposed to the heating element used in recirculated mashing systems. If the heating element is not properly selected there is a risk that the enzymes will be exposed to high heat and subsequently denatured.
In practice, the total time when the heated wort is higher than the bulk mash temperature is short because the wort is pumped back into the mash and tempered. It is also the norm to select low Watt density heating elements to prevent exposing enzymes to damagingly high surface temperatures. Suffice to say, these systems can be designed to work quite well. Some of the things that could cause problems with these systems include: Heating elements that expose enzymes to very high temperatures, restricted and/or slow wort flow that prolongs the duration of higher temperature exposure, and improperly controlled systems where the heating set-point in the recirculated wort stream is much higher than the mash temperature set point. All of these could result in excessive damage to malt enzymes and negatively influence conversion.
Q
Why do some wheats need to be malted and others, like einkorn, not require a malting process?
Julio Montero
Charlotte, North Carolina
A
Grains are malted so that starch contained in the grain endosperm can be released into solution during mashing. The changes that happen during malting are collectively termed modification. And the thing that unites all of these changes is enzymatic production and enzymatic activity. At the end of the malting process, malted grains contain a wide range of enzymes intermingled with partially digested endosperm material. The partially digested endosperm is a mixture of starch, the primary constituent, cell wall fragments (starch is surrounded by cell walls composed of proteins and gums, commonly referred to as dietary fiber, like beta-glucans and arabinoxylans) and fragments of the protein “glue” that binds the endosperm into a hard kernel. The kilning process dries these goodies and preserves the enzymes, resulting in the ultimate brewing package known as malt.
Most beer brewed globally uses a mixture of malted grain, principally malted barley, and adjuncts. The simplest definition of an adjunct ingredient is anything other than malted barley used to contribute extract to wort. Some brewers lump other malted grains with malted barley and reserve the term adjunct for unmalted grains. The major distinction between malted and unmalted grains is the presence of enzymes; any unmalted, starchy ingredient used in brewing must be mixed with enzymes for starch conversion and the traditional source of enzymes is malted barley.
Long introduction for a short answer: Wheat does not need to be malted for use in brewing and there is a long history of using unmalted wheat as an adjunct grain. And einkorn, like other wheat species, can be used in both unmalted and malted forms.
Raw wheat is different from rice and maize/corn — the most common adjuncts — because the gelatinization temperature of wheat starch is low enough to use in all mashing systems (infusion, step and decoction) without having to be specially treated. I am intentionally avoiding specific values for the gelatinization temperature because gelatinization occurs over a temperature range and is affected by mash thickness and varies with grain variety, be it wheat, rice, corn, barley, etc. The take home message is that raw wheat can be easily used in mashing, whereas rice and corn have to be gelatinized, usually by boiling, before they can be added to the mash.
The thing about wheat is that, like barley, it is relatively easy to malt. And unlike barley, wheat sheds its husk easily during harvesting. The term “separate the wheat from the chaff” refers to threshing where the valuable wheat endosperm is separated from the low-value chaff. Since wheat loses its husk, a husk source is required when malted wheat, or a combination of malted and unmalted wheat, is used for brewing. The easiest source of husk material is malted barley, but some brewers add rice hulls to 100% wheat mashes. Malted wheat can be kilned to yield a very pale, enzyme-rich malt that works great for pale wheat beers, or specially kilned to yield darker special malts, such as caramel wheat, chocolate wheat malt, and black wheat malt.
In a nutshell, wheat is a very versatile brewing material with lots of advantages. 2016 marks the 500-year anniversary of the Reinheitsgbot; a law that prevented normal brewers from using wheat as an ingredient because wheat was, and continues to be, a very important foodstuff. This restriction was not applied to state run breweries because the wealthy, ruling class really liked wheat beers and did not want this law cramping their style. So in celebration of this 500-year-old beer purity law, make 2016 the year of the wheat beer and brew with wild abandon!
Q
I have now completed my first successful batch of homemade beer and am excited to move on to new things. It took me nearly four years between a failed batch of vinegar-tasting stout to try again but now I have had a success. Over these past few years I have done plenty of reading and thinking on the processes I would use once I got into brewing on a regular basis. Now it would appear with my first success that this will become a regular thing and I have always had it in my mind to age a beer in a 5-gallon (19-L) oak barrel, possibly from a bourbon producer. From all I have read, it would appear as though those barrels are pretty much a one-time use. Is this true? If so, with such a large investment into a one-time use, what styles would you recommend for use in the barrel? I am not meaning what styles are commonly used but instead, if I am to try this experiment for my first time is there a style that would be better than another? I prefer heavy, dark beers but still love all styles and appreciate each for their own individual characteristics.
Jason Munson
Savannah, Georgia
A
One of the most common beer types to age in bourbon barrels is strong stout. The rich, roasted flavors from the stout marry well with oak, vanilla, coconut, and Bourbon notes from the barrel. Additional layers of complexity can be gained by blending fruit-aged stouts to the mix. Other strong beers with a sturdy malt backbone, such as barleywine and Scotch ale, are also commonly aged in used Bourbon barrels. The nice thing about these big beers is that they often
times oxidize with grace, developing Sherry and dark fruit flavors that work well with the complexity of the Bourbon flavors.
But big, robust beers are not the only things being aged in Bourbon barrels. Lighter colored beers with moderate alcohol levels, sour beers, and dry ciders can work very well with barrels. It really is a matter of bringing together flavor combinations that result in a beautiful blend.
There are challenges involved in this process, with the list header being finding a barrel for your project. Although smaller distilleries, especially new companies wanting to quickly get their product to market, sometimes use small barrels, the norm is to use larger barrels. All Bourbon, by legal definition, is aged in new American oak barrels, thereby guaranteeing a constant flow of used Bourbon barrels. These barrels are used to age all sorts of beverages, including Scotch, rum, tequila, and beer. With the growth of Bourbon-aged beer the supply of Bourbon barrels has tightened up, but it is still pretty easy to find them if you are only looking to buy a small quantity. Finding wet, small barrels can be more of a challenge.
Jargon note: The term “wet barrel” is industry lingo for barrels that have been emptied, yet still contain Bourbon in the sponge-like wall of the barrel and sometimes even sloshing in the bottom. You want a wet barrel when making Bourbon barrel beers.
Beginning with excellent beer is required. Period. Anything else is simply too much of a gamble. If the beer intended for barrel aging has flavor flaws, they will likely persist in the finished beer. Sure, the Bourbon barrel flavor may disguise flaws, but for such an expensive beer, the threat of aging a subpar beer is simply too much of a risk.
The beer also needs to be very clean because the extended aging process gives bacteria and wild yeast time to spoil beer. But even excellent, clean beer can spoil during aging because Bourbon barrels can harbor spoilage bacteria. Recently, there have been several product recalls of commercially-produced barrel-aged beers because of off-flavor development in the bottle. This has prompted many of the larger producers of these beers to add pasteurization equipment to guard against this sort of problem.
The exciting thing about aging beer in Bourbon barrels is that the transfer of barrel flavor to the beer occurs fairly fast, especially when using small barrels for the first time. Think 4-6 weeks, not 4-6 months. Sampling is important and the easiest way to remove samples from a barrel is through a nail hole; just make sure you use a stainless steel nail and to remember to drill the hole and install the nail before filling your barrel! Then you just pull the nail out and collect a sample of what’s aging inside.
You can certainly use a Bourbon barrel more than once and continue to extract Bourbon flavors into beer, but the second, and perhaps third use, results in less Bourbon aroma and takes longer to extract the flavors. Subsequent uses will also increase the risk of beer spoilage.
OK, now for some advice on jumping into barrel aging that you may not want to read . . . put this plan on the shelf and pull it down after you have more homebrewing experience. You relay a bad experience with a vinegar-laden stout that kept you away from homebrewing for four long years. Don’t set yourself up for another potential disappointment!
Success with one batch is not enough to prepare for the bourbon barrel challenge. You need to successfully brew several batches, at least five to ten, to get ready. This will do two important things. The first is that it allows you to prove to yourself that you have the whole cleaning and sanitizing routine mastered well enough to produce normal beer. These successes also will help you to keep your previous failure in the past and will help prepare you for a potential failure. Failure is a real possibility when aging in a barrel and you need to feel good about your process and ability to brew. Remember that excellent, clean beer can be ruined by a bad barrel and, unless you have a beer microbiology lab equipped to screen your barrel, there is no way to know if you have a good or bad barrel.
When you are ready for your first Bourbon barrel beer, knock on wood and let ‘er rip! Chances are that you will be very happy with the outcome.
Q
I am wondering what information there is on doing a double filtration of my homebrew. I have to perform a secondary and thought I could filter at 5 microns. Then when the secondary was done, I could filter at 1 micron to filter out the yeast. Is that a reasonable way
to filter homebrew for kegging? I’d like to know if there are better ways to filter as well.
Christopher Wright
Osage, Iowa
A
The first question that really should be answered is why do brewers filter beer? Some brewers filter beer to make it clear and pretty, some filter beer so that they don’t have to wait weeks for yeast to settle out and want the yeast out for flavor reasons, others use sterile filtration to guard against beer spoilers that may be in their beer and other brewers filter because most beer is filtered and they are simply going with the flow. All of these reasons, except for the last, are good reasons to filter as long as these reasons are aligned with your needs. But if you want to filter just for the sake of filtering, you really should reconsider your reasoning.
The fact about filtration is that it can both frustrate you and quickly damage your beer in one fell swoop if performed improperly. Large volume filtration is often conducted in stages where the first stage is performed using diatomaceous earth or perlite as a filter aid in a type of a filter commonly referred to as a powder filter. In this sort of filter, the filter aid (diatomaceous earth or perlite slurry) is metered into the beer stream as the beer enters the filter. This allows the filter aid and the yeast to develop a filter cake on the filter during the course of filtration. A secondary sheet filter is used to then “polish” or make the beer very bright, and sometimes a third filter pass using a membrane, sterile filter is used prior to packaging. At home, powder filtration is extremely uncommon.
The most common filters used at home and by smaller scale commercial brewers are sheet filters and wound, hollow-core filters. These filters do have limited sludge capacity because they have some thickness and solids can be trapped within the filter depth, like powder filters. Starting out with well-settled beer is very important when using low-capacity filters because blinding the filter with excessive yeast is a real problem that requires the filtration process to be terminated and the filter replaced. In the process of replacing the filter, beer loss is also pretty common. Yeast cells are about 10 microns in diameter and can be removed with filters in the 5–10 micron nominal size rating. Nominal rating means the filter removes particles in the size range, with pores that are actually larger than the nominal size. In filter jargon, depth filters function by trapping particles in a “tortuous flow path.”
Secondary filters are typically used to either polish beer or to remove bacteria. Polish sheet filtration can be accomplished using filters with a nominal rating of 1–5 microns. The primary purpose of polish filtration is the removal of haze, since almost all of the yeast is removed by primary filtration. The thing to consider here is that you are likely to strip the beer with filtration and stripping is increased as pore size decreases. Bitterness, mouthfeel, foam, flavor intensity, hop aroma, and color all can be affected by filtration. Beers that are always filtered are often “tweaked” so that the filtered beer has the attributes desired by the brewer.
Finally there is membrane filtration that can be used for sterile filtration. In the beer industry the term sterile filtration means that the pore size of the membrane is no larger than 0.45 microns. Sterile filtration can be tricky with all-malt beers because gums, such as beta-glucans, can quickly blind sterile filters. Unlike filter sheets, membrane filters have no sludge capacity and quickly go from flowing to not flowing when the pores are plugged.
The easiest way to filter your keg is to use a hollow-core filter with a nominal pore size in the 5-10 micron rating. A sheet filter system using a plate filter housing can also be used, but these are more expensive and not as common for small-scale, periodic filtration. You can set both of these filters up by packing the system with water and blowing the water out with carbon dioxide before filtration. This step is really important; if you are not thorough with your flushing you can very easily oxidize your beer and convert excellent, cloudy beer into oxidized, disappointing, clear beer. Once the filter is set up, all you need to do is push the unfiltered beer from one keg to another using carbon dioxide pressure. If you are going to use a secondary filter, then you repeat the process.
This whole filtration process works best if you allow your beer to settle in your primary for at least a week after fermentation is complete before racking to a keg. And filtering the beer as cold as possible results in the clearest beer.
